Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933925AbaLKLlP (ORCPT ); Thu, 11 Dec 2014 06:41:15 -0500 Received: from metis.ext.pengutronix.de ([92.198.50.35]:44338 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753242AbaLKLlN (ORCPT ); Thu, 11 Dec 2014 06:41:13 -0500 Message-ID: <1418298046.3188.10.camel@pengutronix.de> Subject: Re: [PATCH 2/2] misc: sram: switch to ioremap_wc from ioremap From: Philipp Zabel To: Will Deacon Cc: Abhilash Kesavan , Santosh Shilimkar , Tony Lindgren , Catalin Marinas , "heiko@sntech.de" , "Li.Xiubo@freescale.com" , "shc_work@mail.ru" , "nicoleotsuka@gmail.com" , "arnd@arndb.de" , "gregkh@linuxfoundation.org" , "robh+dt@kernel.org" , "grant.likely@linaro.org" , "linux-kernel@vger.kernel.org" , "corbet@lwn.net" , "padma.v@samsung.com" , "alsa-devel@alsa-project.org" , "shawn.guo@freescale.com" , "bcousson@baylibre.com" , "tony@atomide.com" , "kernel@pengutronix.de" , "kgene@kernel.org" , "kesavan.abhilash@gmail.com" , Pawel Moll Date: Thu, 11 Dec 2014 12:40:46 +0100 In-Reply-To: <20141211103919.GA6067@arm.com> References: <1418266726-12004-1-git-send-email-a.kesavan@samsung.com> <1418266726-12004-2-git-send-email-a.kesavan@samsung.com> <1418292513.3188.4.camel@pengutronix.de> <20141211103919.GA6067@arm.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.7-1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 2001:67c:670:100:96de:80ff:fec2:9969 X-SA-Exim-Mail-From: p.zabel@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Will, Am Donnerstag, den 11.12.2014, 10:39 +0000 schrieb Will Deacon: > On Thu, Dec 11, 2014 at 10:08:33AM +0000, Philipp Zabel wrote: > > Hi Abhilash, > > > > Am Donnerstag, den 11.12.2014, 08:28 +0530 schrieb Abhilash Kesavan: > > > Currently, the SRAM allocator returns device memory via ioremap. > > > This causes issues on ARM64 when the internal SoC SRAM allocated by > > > the generic sram driver is used for audio playback. The destination > > > buffer address (which is ioremapped SRAM) is not 64-bit aligned for > > > certain streams (e.g. 44.1k sampling rate). In such cases we get > > > unhandled alignment faults. Use ioremap_wc in place of ioremap which > > > gives us normal non-cacheable memory instead of device memory. > > > > Could this break the omap_bus_sync() implementation in > > arch/arm/mach-omap2/omap4-common.c? > > > > void omap_bus_sync(void) > > { > > if (dram_sync && sram_sync) { > > writel_relaxed(readl_relaxed(dram_sync), dram_sync); > > writel_relaxed(readl_relaxed(sram_sync), sram_sync); > > isb(); > > } > > } > > > > It is used in wmb() and omap_do_wfi() to drain interconnect write > > buffers on omap4/5. If sram_sync is mapped with write-combining, could > > the last write to sram_sync stay stuck in the write-combining buffer > > until after the function returns? > > I think you have that issue anyway, since you can get an early write > response even if you use ioremap. Does the write to sram_sync have > side-effects that we need to wait for? [Added Tony Lindgren and Santosh Shilimkar to Cc:] I don't know. regards Philipp -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/